1. Field of the Invention
The present invention relates generally to surgical devices and methods for repair of torn or avulsed soft tissue. More particularly, the present invention relates to a device and method for the secure fixation of torn or avulsed soft tissue to soft tissue and to bone.
2. Description of Related Art
It is not uncommon for tendons and other soft tissues to tear or detach from bone. Athletes, for example, often suffer orthopedic injuries such as torn or ruptured tendons and/or ligaments. For example, in the shoulder, a common injury is a torn rotator cuff in which a portion of the rotator cuff tendons tear within themselves or avulse from their insertion into bone. A torn rotator cuff can cause pain, weakness and loss of function.
In many cases, these symptoms can be relieved by surgically repairing the tear. This requires repairing any interstitial tears in the soft tissue (tendons, ligaments, and muscle) as well as approximating the torn edge of the soft tissue to the bone where it originated.
Current methods for reattaching soft tissue to bone use suture fixation, spiked soft tissue plates or staples at the torn edge of the tendon. Suture fixation of the tendon is the most common and classic method. In the case of tissue avulsing from bone, the torn free edge is typically debrided to clean up the edge before reattaching the edge to the bone. The torn free edge of the tendon, however, is usually poor quality tissue because it is usually involved in the degenerative process that is commonly involved in these tears. Improvements in the methods and devices to reattach soft tissue to bone have resulted in the soft tissue side of the repair when utilizing suture anchors becoming the weakest link of the overall construct.
Generally, in the repair of soft tissue, sutures are placed into soft tissue. A problem with this technique is pull-out of the sutures. It has also been observed that sutures applied to the tendon may strangulate and/or pull out the tendonous tissue. When this occurs, the suture material may stay intact but the tendon is connected to the bone through functionally insufficient scar tissue. This is particularly problematic in rotator cuff repairs, where scar tissue may limit mobility or reduce the strength of the soft tissue.
To lessen the risk of failure from pull-out of the sutures from the soft tissue, prior art methods incorporate various suture techniques and configurations. More complicated techniques such as the modified Mason-Allen stitch, call for weaving the suture back and forth in the tissue, accessing the more normal tissue proximal to the tear. While this is a stronger construct that the simple suture, there is a concern of strangulating the tissue with multiple weaves, resulting in necrosis of the tendon. Further, this technique does not lend itself to arthroscopic repair of the tear.
Other techniques used to combat the problem of suture tearing through tendon are limited to soft tissue buttons (as described in U.S. Pat. Nos. 5,306,290, 5,951,590 and 6,074,409, and the “TissueButton” by Arthrex), plates (as described in U.S. Pat. No. 6,093,201) or washers (as described U.S. Patent Nos. D0404128 and 6,206,886) that increase the effective surface area of the suture contact with the soft tissue and also aid in pressing the soft tissue against the bone at the repair interface. This type of tendon augmentation has been shown to resist failure perpendicular to the tendon fibers but does not reduce tendon shear parallel to the fibers, which is the failure mode when sutures tear through tendon.
There is also difficulty with suture placement in areas that are difficult to access surgically. In the case of rotator cuff injuries, traditional methods usually access the edge of the rotator cuff where tissue quality is poor. The more proximal tissue, which is generally healthier, is difficult to reach and usually not accessed.
Several other devices and techniques offer alternatives to suture fixation, including: screws, screws with spiked washers, plates, tacks, and staples. Screw and tack fixation have been shown to allow adequate fixation of tendon to bone. The soft tissue side of the repair is addressed by using either a broad flat head as part of the screw as in the “Headed Bio-Corkscrew” by Arthrex, or using a separate spiked washer to engage the soft tissue as in the “Biocuff” by Bionix. Tacks such as the smooth and spiked “Suretac” by Acufex address the soft tissue side identically. Patented devices in these categories include those described in U.S. Pat. Nos. 5,013,316, 5,380,334, 5,601,558, 5,370,661, 6,096,060, 5,167,665, 5,893,856 and 5,013,316. Spiked washer technology (such as described in U.S. Pat. Nos. 4,988,351, D0374287, D074482, D0374286 and D0368777) with screw fixation to bone has a long history in other applications such as knee ligament reconstruction and conceivably offers some advantage in resisting pull-out of the screw shank through those tendon fibers parallel to the direction of pull of the tendon. A common problem with the afore-mentioned technology is that the point of fixation of the soft tissue is at the free torn edge, which as noted above is poor quality.
Security of tissue fixation is an important element, particularly in rotator cuff repair. Current methods of obtaining fixation on the soft tissue side of the rotator cuff repair site are limited in their effectiveness by several factors. The free torn edge of the tendon is usually of relatively poor quality, as it is involved in the degenerative process leading to the tear. Arthroscopically placed simple sutures and all the non-suture devices discussed above gain fixation at this free torn edge. More complicated weaving sutures can overcome this problem by accessing more proximal tissue, which is healthier, thicker and stronger, but as noted above, this may be at the expense of tissue necrosis and does not lend itself to arthroscopic techniques.
It is therefore desirable to use a method, system, or device that improves the quality of soft tissue repair by utilizing the healthy areas of soft tissue, resisting shear forces, and increasing the pull-out strength of sutures. It is further desirable to employ a system or device that can be applied arthroscopically.
It is an object of the present invention to provide a method for improving the quality of soft tissue repair by using a soft tissue cleat capable of: attaching to strong, healthy soft tissue; distributing forces exerted on a suture over a larger area of the soft tissue; and increasing the pull-out strength of a suture.
It is another object of the present invention to provide a system for reducing stress on soft tissue by distributing forces over a larger area through the use of soft tissue cleats capable of gripping soft tissue and providing an attachment site for sutures.
It is another object of the present invention to provide a plurality of soft tissue cleats which may be configured to align or overlap along the soft tissue tear in such a way as to minimize stresses and forces at any given point or in any given area of the soft tissue.